Lens-surface grinding and polishing machine



Dec. 7,1926. 1,609,963

E. G. ROBINSON LENS SURFACE GRINDING AND POLISHING MACHINE Filed August 12 1921 .5 Sheets-Sheet 1 De c. 7 1926.

E. ROBINSON LENS SURFACE GRINDING AND POLISHING MACHINE Filed August 12 1921 3 Sheets-Sheet 2 4 f a m M 27" 6 Z 5 J U0 O L. e n r. a a :w

Dec. 7 1926.

E. G. ROBINSON LENS SURFACE GRINDING AND POLISHING MACHINE Filed August 12 I 1921 3 Sheets-Sheet masts PATENT OFFICE.

ERDIS G. ROBINSON, OF COLUMBUS, OHIO.

LENS-SURFACE GRINDING AND POLISHING MACHINE.

Application filed August 12, 1921. Serial No. 491,808.

My invention relates to'lens surface grinding and polishing machines and has to do particularly with the type designed for grinding and polishing cylinder and tone lenses, although not necessarily limlted thereto. In this particular type of machine, the grinding tool or. lap and the lens-holding tool or lens block must retain certain relative axial positions during the grinding process while at the same time maintaining the relative movements necessary to ensure a true grinding of the lenses and an even wearof the tool.

My invention has to do primarily with the provision of a mechanism of a simple and substantial nature wherein the parts are arranged so as to be protected from the abrasive material generally used with machines of this type. I have provided a number of novel characteristics that make possible innumerable adjustments of a highly desirable nature in this type of machine.

My structure of machine is such that an entirely novel relative movement between the lens grinding lap and the lens block will result from the normal operation of the machine. Broadly stated, I have provided a mechanism whereby the lens block is caused to have a rotary movement and simultaneously travel in a non-circular path about the lens grinding lap. I preferably A further feature of my invention has t do with the provision of a single means for adjusting the length of the reciprocation of the grinding lap and the length of the oscillation of the lens block. Ihave further provided structural features which permit of adjusting the length of the oscillation of the lens block without varying the length of the reciprocation of the grinding lap, this being particularly desirable in the grinding of lenses of varying sizes. In addition, the structure last named makes possible the center of its reciprocatory adjustment of the path or center of reciprocation of the grinding lap without varying the length of such reciprocation, al

though it will be obvious that individual means may be provided for effecting this last-named adjustment. There are many other features of my in vention that Will appear as this description progresses or that will be brought out by the claims appended hereto. jects of my invention are attained by the mechanism illustrated in the drawings wherein similar characters of reference designate corresponding parts and wherein Figure 1 is a side elevation partly in section and with parts broken away showing the machine practically in its entirety.

Figure 2 is a detail plan view of the rear portion of the machine showing the movement of the head-carrying arm around the vertical drive shaft.

Figure 3 is a transverse vertical section taken on line 33 of Figure 1.

Figure 4 is an enlarged detail sectional view on line 44 of Figure 1, setting forth the means by which the adjustments for various sizes of lenses and laps is accomplished.

Figure 5 is a section taken on line 5-5 of F i ure 4.

Figure 6 is a section taken on line 66 of The various ob- 10-10 of Figure 9, looking in the direction of the arrows.

of the head.

Figure 12 is a diagrammatical view showing the rotary movement of the lens block at the start of its oscillatory movement across the lap and showing the lap at the th of travel.

Figure 13 is a diagrammatical view showing the lens block at its center of oscillatory travel and the lap at its extreme outward Figure 14 is a diagrammatical view showing the lap block at the end of its oscillatory throw.

Figure 15 is a diagrammatical view showas in Figure 12 and the lensd ing the lap at its inner position and the lens block at the center of its return oscillatory movement.

Figure 16 is a diagrammatical view representing the path of a central point on the lens in its travel. over the surface .of the lap.

Figure 17 is a modified detail of my grinding lap mounting wherein the lap is designed to be used without movement.

In the drawings, most of the driving and operating mechanism is housed in the base 1, with its sides 2, front and rear walls 3 and top 4. The machine as a whole may be roughly divided into two parts, the lap operating mechanism and the lens block operating mechanism, bothof which are driven primarily from a transverse horizontal drive shaft 5, journaled in boxes in the sides 2, and having on one end a pulley 5 for connection by belt with a suitable source of power. The shaft 5 also carries a friction drive Wheel 6 which cooperates with a friction disk 7,

- rigidly disposed on the lower end=of a vertical shaft 8. On the upper portion of the vertical shaft 8 is keyed a pulley 9, over which a beltlO passes to a similar pulley 11 located in the lens block operating head 12.

The shaft 8 has a bearing in a sleeve 13 which in turn has a bearing in a post 14 rising from the top 4 of the base structure. The sleeve 13 forms the vertical leg of a right-angled member 15, the horizontal leg 16 of which is bored as at 17 to receive a pin 18 extending from the head 12 and, which in connection with a set screw 19 serves to hold the head in any desired position. Normally, however, the head stands vertically. In order'to tighten the belt 10, it is necessary to loosen the set screw 19, whereupon the turning of a thimble 112 threaded upon the end of the leg 16 and bearing against the shoulder 113 presented by the head 12, forces the center of the pulley 11 a greater distance from the pulley 9. An eye 20 is formed as shown at the juncture of the legs 13 and 16 to receive and hold the pulley 9.

On the extreme lower end of the shaft'8 is a worm" wheel21 which meshes with a worm gear 22 mounted on the shaft 23. Shaft 23 is carried in bearings 24 in the end walls 3 of the base. This shaft 23 cooperates with a shorter but parallel shaft 25 in supporting a framework 26, which in turn carries the final drive and adjusting mechanism to be presently described.

Referring to Figures 1 and 4, it will be seen that the grinding lap 27 is carried in a socket 28 of a sliding carriage 29. A pair of rods 30, hung from the underside of the top 4, forms the guides for the carriages 29 by passing through the two pairs of ears 31 of said carriage. The socket portion of the carriage 29 extends up through an elongated opemng 32 in the top 4 to permit the lap in a horizontal circle, it will be seen that the carriage 29 will be constrained to move backward and forward along the rods 30 and its length of motion definedby the diameter of the circle in which the pin 36 travels.

The pin is the offset portion of a crank pin designated in its entirety as 37, the longer portion 38 of which extends through an eccentrically bored sleeve 39 journaled in the framework 26 as shown at- 40. Midway on the sleeve 39 and between the bearings 40, is located a Worm gear 41 which meshes with a worm 42 slidably keyed 0n the shaft 23. End thrust of the worm is taken up and the worm is held in longitudinal alignment with its gear by a pair of ball bearings 43 loosely mounted on the shaft 23. The whole framework 26, with its operating parts, it will be remembered, is partially carried by the shaft 25. This shaft is threaded on its inner end as at 44 into a lug 45 extending inwardly from wall 2 of the base and is support-ed at its outer end by passing through the front wall 3 as at 46. The outer end of the shaft 25 is squared as at 47 to receive a wrench or crank. Midway on the shaft 25 and on either side of an ear through which the shaft 25 passes are pinned two collars 49. Thus, by turning the shaft 25 in either direction, the framework 26 will be constrained to move backward or forward along the shaft 23 because of the operation of the threads 44. This adjustment moves the centerof the reciprocating movement of the lap 27 but does not affect the length of the movement as 'determined by the action of the pin 36.

In order to vary the diameter of the circle in which the pin 36 operates and thereby change the length of the reciprocating movement of the lap 27, a six-jawed clutch 50 is provided which consists of two jaw members 51 and '52. The member 51 is rigidly fastened to the sleeve 39 as shown at 53, while the cooperating jaw 52 is slidably keyed to the portion 38 of the crank pin 37. Both jaws, to be in proper working alignment, are disposed concentrically of the pin 38 as is shown in Figure 4. .In the operation of the machine, the clutch is normally in engagement so that the crank pin 37- is constrained to move as a unit with the sleeve 39 under the influence of the motion imparted by the shaft 23, through the worm gearing 41 and 42.

Referring particularly to Figure 5, the effect of turning the crank 'pin 37 in the sleeve 39 may be seen. The position of the pin 36 shown in full lines is much farther from the center of rotation of the sleeve 39 than is the ,position of the pin 36 shown in dotted lines after the crank pin 37 has been turned approximately 120 degrees in the sleeve. The number of positions assumable by the crank pin in relation to the sleeve is determined by-the number of jaws in the clutch. In this case, three different positions are possible due to the six-jawed clutch.

To operate the clutch, a lever 54 is provided which is fastened at one end to a transversely extendingrod 55 mounted between sides 2 of the base. The front end of the leverprotrudes through a slot in the end 3 of the base .and terminates in a handle. Owing to the fact that the clutch revolves eccentrically while the machine is in motion,

-the connection between the lever 54 and the jaw member 52 must be such that will allow the jaw 52 to be released from engagement with the jaw 51 and yetnot transmit the eccentric motion to the lever in the form of a vibratory movement. In the drawings, a T-shaped block 118 is slidably mounted on the lever 54, with the leg- 119 of the T- shaped block carrying a short pin as at 56. This pin passes freely throughan ofl'set portion 57 of a collar 58 which surrounds the lower reduced portion or neck 59 of the clutch jaw 52. A washer fastened to the aw as at 60 preventsundue play of the co ar 58 and causes downward pressure on the collar to disengage the clutch 50. All eccentric movement in a horizontal plane is efiectually absorbed and yet vertical movement on the part of the lever 54 engages or disengages the clutch. Owing to the fact that the rotation of the clutchparts is habitually slow, and to the fact that the jaw 52 stops upon disengagement while jaw 51 continues to rotate, reengagement. at any point after disengagement of the clutch can be easily effected to change the throw of the pin 36 the desired amount. Normally, the clutch is held in engagement by'a spring61.

It will be noted that the pin 36, in addition to operating the block 35, also passes through a block 62. This block 62 slides on the forward end of an actuating rod 63 which has its rear end fixed in a knuckle 64 set-screwed on the lower portion of the sleeve 13. The sleeve 13 extends below the under surface of the post 14 expressly for the pur-' pose of receiving the knuckle 64 and the actuating rod 63. Thus, the eccentric pin 36.

is enabled to impart "an oscillatory movement to the lens block operating head at-the same time and in the same manner that it reci'p'rocates the lap carriage 29. Confined in the knuckle 64 and surrounding shaft 8, is a spring 65 which forces the friction disk 7 into engagement with the wheel 6; friction between the revolving disk and the knuckle being eliminated by a ball bearing 66. Upward thrust of the spring is" transmitted through the knuckle to the base of the post 14 as at 67.

To utilize the friction drive mechanism as shaft 8 and the handle 71 on a transverse rod 69. a

It has been stated that the belt 10 passes over a pulley 11 located in the lens block operating head 12. Specifically, the pulley 11 is mounted on a vertical spindle 74, which in turn is both rotatably and slidably jour' naled in the head 12. The upper bearing 75 is in the reducedportion of the head itself while the lower bearing 76 is in the shape of a sleeve 77 carried by a wide flange 78, by which it is attached to the head 12. Three screws 79 are the attaching means. The flange or plate 78 also serves to confine the pulley 11 between the shoulders 80 and. 81 of the head and flange, respectively. Free end play of the spindle 74 through the pulley is permitted by a sliding key connection 82 between the pulley and the spindle.

The head 12, as shown in Figure 1, is some distance above the grinding lap, but the spindle 74 extends below the head and terminates in a pointed pin 83. The lens block 72, used in conjunction with the present machine, is of the type having a pair of arms extending from opposite sides of the body as at 73, Figure 8, and has a conical indent in the center of its upper surface for the reception ofthe point of the operating pin 83. To the opposite or under surface of the lens block, the glass to be ground or polished may be cemented in the usual manner. To give a rotary motion to the lens block, the pin 83 is fixed off-center in the end of the spindle 74 as is clearly shown in Figure The pressure necessary to hold the pin 83 in engagement with the lens block and to utilize the abrasive action of the lap efficiently is provided by a spring 84 confined 'in the upper tubular portion 85 of the spindle 74. While the downward pressure of the spring-operates against the spindle, the upward thrust is exerted against the end of a plunger 86 which enters the tubular portion of the spindle through a reduced opening in a screw plug 87, The plunger 86 passes up through the extreme top of t pressure head casting which is split at that point, as indicated at 88, to form a clamp to hold the plunger 86 firmly in any position of adjustment, and terminates on top in a hand-knob 89. A hand-nut and bolt construction 90 (Figure 9) serves to actuate the clamp. It will be noted that the plunger 86 is enlarged at the point 91 where it contacts a itli the spring. with the reducing plug 87, limits the expansion of the spring and makes itpossible to raise the spindle entirely out of engagement with the lens block. Downward pressure on the hand-knob 89, after the pin 83 is seated on the lens block, however, increases the pressure exerted by the spring to the point desired, when the plunger 86 can be locked by operation of the hand-nut 90 and the retained during the continued operation of the machine.

It has been stated that in machines, such as the present onefor grinding toric and cylinder lenses, the grinding lap and the lens being ground must retain certain relative axial positions during the grinding operation. By this is meant that a line scribed on the lens along its cylinder or toric axis must remain parallel or at any given angle to a similar line scribed on the grinding lap. This explanation is somewhat inaccurate when applied to toric lenses inasmuch as the axis of a toric lens assumes varying degrees of inclination in a vertical plane during the grinding operationdue to i the curvature of the toric lapin tte axial direction. In such cases it is understood to be the vertical plane in which the toric axis travels that must remain in a given relation to the toric axis of the lap. My improved mechanism for accomplishing the operation described above consists of the following main elements which can be located by particular reference to Figures 7, 8,9, 10 and 11, parallel arm 92, sleeve 93, yoke-bearing collar 94, yoke and the pair of lens block engaging arms 96. The bearing sleeve 77 carries the sleeve 93, which in turn carries the yoke-bearing collar 94. A nut 97 on the sleeve 93 locates the collar'94, while a.

similar nut 98 on sleeve 77 retains the sleeve 93 in place. These nuts 97 and 98 bear against shoulders 99 on their respective sleeves and so permit free relative turning motion of the several parts on each other. Normally, however, the collar 94 acts rigidly with sleeve 93, due to set screw 100, tightening of which locks parts 93 and 94 together.

This construction, in connection tions 103 and 104 are designed to form the corners of a parallelogram which is maintained in spite of the oscillation of the head In the middle portion of the yoke 95 and to the rear of the pivoted axis of the yoke, is a spring-pressed plunger 109 tending to turn the yoke about its pivot and to press the lower ends of the arms 96 forward into engagement with the arms 73 of the lens block, after the manner shown in the drawings. The plunger 109 bears against an extended wing 110 of the bearing flange 78. The wing is extended approximately a quarter of the way around the periphery of the flange so as to present its surface to the plunger 109 at whatever operative position the plunger should be.

It may be explained here that it is sometimes necessary to change the position of the lens axis from the normal or parallel position with respect to the axis of the lap and that this deviation is usually accomplished at the time of cementing the lensto the lens block. In the present machine, however, the corrections may be accomplished at any time after the lens is affixed to the block, by loosening set screw and turning the collar 94 the desired number of degrees as indicated on a scale 111. This turns the lens block as well as the lens and easily, quickly and accurately makes the correction. It is understood that the axis of the lap is always fixed parallel to the frontedge of the machine, the usual method being to fitthe square shank of the lap into a square socket 28. I t

The mechanism herein set forth for keeping the arms of the lens block vertically parallel to a given line, I regard as desirable for the reason that wear of the arms 96 and 73 has no effect on the accuracy of the results; The spring-pressed plunger 109 keeps the arms 96 and 73 in firm engagement at all times, whereas in the usua-l'construction of double or forked arms passing on each side of the arms 73, wear will soon cause the lens block to wabble, with consequent inability of the machine to perform accurate work. Furthermore, the lens block is easily laced in or removed from its operative position by merely lowering or lifting the spindle 74 and no time is required to place the arms 73 between a pair of forks.

Reference to Figures 12, 13, 14 and 15 will help to show the motions of the lap and lens block arising from the rotation of the crank pin 37 and the eccentric pin 83. In Figures 12, 13, 14 and 15 the path of the lap 27 is along the center line 114, and the path of the lens block operating head along the arc 115. The dotted circles indicate the rotary motion of the lens block due to the eccentric pin 83. In Figure 12, the lens block 72 is at the limit-of its oscillatory motion and starting to return in the direction of the arrow 116, and the lap 27 is at the center of its reciprocating motion and moving in the direction of the arrow 117. In Figure 13, the crank pin 37 has advanced a quarter turn; in Figure 14, a half turn: in Figure 15, three quarters of a turn and one com plete turn would place the lap and lens block in the relative positions indicated in Figure 12, ready for another complete cycle of operation. It will be seen that at all times the edge of the lens touches in its rotary motion both the center and periphery of the lap so that during one complete turn of the crank pin 37 the lens has completely and evenly traversed the surface of the lap. Thus, uneven or irregular wear of the lap is eliminated. To make this possible with various sizes of lenses and laps is the function of the clutch 50, by which the length of the re ciprocating and oscillatory movements of the lap and lens, respectively, are suitably changed, as hasbeen previously described.

Figure 16 depicts the approximate path of a center point on the lens in its travel over the lap. There are no speed reductions between shaft 5 and spindle 74 as there are between shaf 5 and crank pin 37. -Therefore, the rotary movement of the lens block is very much more rapid than the travel-of this lens block in its non-circular path about the lap axis. By reference to Figure 16 and particularly to the center thereof, it will be apparent that the travel about the axis of the lap is non-circular or in the nature of a distorted circle, the distortion being due .primarily to the curved path of travel of the lens block in its swinging action.

The function of the adjustment provided by the threads 44 on shaft 25 is to bring the center of rotation of the sleeve 39 directly 1 under the path of the center of rotation of the spindle 74, particularly after the spindle 74 has been moved by ti htening the belt 10.

A modified form of my grinding lap structure is shown in Figure 17 The grinding lap socket 28 forms a part ,of the top 4 ofthe base 1 and is thus held stationary and rigid. The eccentrically journaled shaft 38, and its crank 37 and crank pin 36 are designed to oscillate the rod 63 about the lens .block operating head shaft 8. Connectin the in 36 and the actuating rod 63 and slida 1y mounted thereon isthe block 62.- In operation, the rotary action of the sleeve stood that adjustment of the frameworkshifting rod 25 will change the radius of.

the block 62 and, thus, give a more accurate adjustment of the oscillatory throw of the lens block head in'combination with the automatic adjustment by means of the clutch 50.

Having thus described my invention, what I claim is 1. A machine of the character described comprising a lens block, a lap, means for reciprocating said lap in it straight line and oscillating said block in a curved line, means for bodily rotating said block and means for adjusting said block-to predetermine the position of the cylindrical axis of the surface to be ground upon the lens.

2. A machine of the character described.

comprising a reciprocatory lap, an oscillatory and bodily rotatable lens block, means for adjusting said lens block to predetermine the position of the toric or cylinder axis of the surface to be ground upon the lens, means for bodily rotating said block, means for reciprocating said lap and oscillating said block, and means for maintaining .the toric or cylinder axis of the surface to be ground upon the lens in planes arallel to the toric or cylinder axis of the said lap and to each other.

3. A machine of the character described comprising a lens block, a lap, means for reciprocating said lap in a rectilinear path and oscillating said block in a curvilinear path across the path of said lap and means for bodily rotating said block.

4. A machine of the character described comprising a lens block, a lap, means for oscillating said blockin a curved path about a fixed center upon the surface of said lap,

5. A cylinder lens grinding machine comprising-a reciprocatory cylinder lap, a lens block, means for oscillating said block in a curved path upon the surface of said lap and means for maintaining the toric or cylinder axis of the surface to be ground upon the lens in planes parallel to the toric or cylinder axis of the said lap and to each other. I j

6. Lens grinding apparatus comfprising-a grinding lap, a lens block, means or reciprocating said lap in a fixed path, means for oscillating said lock in a curved path upon the surface of said lap,-and an eccentrically mounted pin for imparting bodily rotation to said block.

7. A lens .grindin machine com rising a lapfa lens carrying lock, means or reciprocating said lap in a single vertical plane, means for oscillating said block in a curved path upon the surface of said lap, means for odily rotating said block and means operatively connected with the said oscillating means for adjusting the oscillatory throw of said block.

8. A machine of the character described comprising an oscillatory and bodily rotatable lens block, means for oscillating said block, means for bodily rotating saidblock, a grinding lap, means for reciprocating said lap and means for cooperatively adjusting the'reciprocatory movement of said lap and the oscillatory throw of said block.

9. A machine of the character described comprising a reciprocatory grinding lap, an oscillatory lens block, means for controlling both the reciprocation of'said lap and the oscillation of said block, and means for adjusting the extent of said reciprocation and oscillation while the apparatus is in motion.

10. A machine of the character described comprising a reciprocatory grinding lap, a

bodily rotatable and oscillatory lens block,.

and mechanism embodying means for bodily rotating said block and for imparting oscillatory movement to said block and reciprocatory movement to said lap. I 11. A machine of the character describe comprising a reciprocatory lap, a bodily rotatable and oscillatory lens block, means for bodily rotating said block, and means for imparting reciprocatory movement to said lap and oscillatory movement to said block, said last-named means being adjustable to simultaneously vary the extent of the reciprocatory movement of said lap and the oscillatory movement of said block.

12. A machine of the class described comprising a reciprocatory lap, an oscillatory lens block, an eccentric pin for simultaneously controlling both the reciprocation of said lap and the oscillation of said block, power driven means for driving said pin in a circular path and means for adjusting the eccentricity of said pin while it is in motion.

13. A machine of the class described comprising an oscillatory lens block, a reciprocating grinding la means for maintaining the toric or cylin er axis of the surface to be ground upon the lens in planes parallel to the toric or cylinder axis of the said lap and to each other, and means for giving said tween the toric or cylinder axes of the lens and the lap.

15. A machine of the character described comprising means for holding the grinding lap and lens block in operative contact, means for automatically moving said block to successive positions around the center of said lap, and a parrallelogram structure including an adjustable thrust rod for adjusting and maintaining the axis of said block in any position parallel with its axis in any oitl-helr position and parallel with the axis of t e ap.

16. A machine of the character described comprising a reciprocatory grinding lap, an oscillatory lens block, means for controlling said reciprocation and oscillation, and means for adjusting said last means to vary the path of said reciprocation without varying its length and to simultaneously vary the len th of said oscillation.

-1 A lens grinding apparatus comprising a lap, a lens block, and means for causing said lap and block to move relative to each other in such a manner that one moves in a straight path in a horizontal plane, and the other moves in a curved path in a substantially horizontal plane.

In testimony whereof I hereby afiix my signature.

ERDIS G. ROBINSON. 

